01 Jan 1970 Story Chemicals & waste

Extraordinary levels of toxic chemicals in the deepest ocean fauna

Extraordinary levels of toxic chemicals in the deepest ocean fauna 

Evidence of environmental pollution by humans on the most remote and inaccessible habitats

Scientists have found extraordinary levels of the toxic polychlorinated biphenyls (PCB) and polybrominated diphenyls (PBDE) in ocean fauna in two of the world's deepest ocean trenches (>10,000 metres). PCB and PBDE are both human-made chemicals that have dangerous effects on the environment and our health. The scientists stress that “the oceans comprise the largest biome on the planet, with the deep ocean operating as a potential sink for the pollutants and litter that are discarded into the seas”.

The finding reveals bio-accumulation of these toxic chemicals through the food chain across the world’s oceans and to full ocean depth. To illustrate the levels found in the Mariana trench in the North Pacific, the scientists state that “the highest levels of PCBs were fifty times more contaminated than crabs from paddy fields fed by the Liaohe River, one of the most polluted rivers in China”.

Bio-accumulation of PCB and PBDE in the remote and deep trenches is explained by transport of these chemicals over great distances through the oceans and atmosphere, association with particulate matter and vertical sinking. The scientists conclude the article insisting to further investigate the consequences and better understand the effects on the ecosystem function.

The discovery was published in Nature’s Ecology and Evolution journal. Click here to access the full article.